The main properties of experimental RFP magnetic profiles are reviewed and discussed in the context of relaxation theory. Relaxation phenomena under conditions of magnetic helicity conservation are a fundamental process determining both the formation and sustainment of the RFP magnetic distribution as well as plasma particle and energy confinement. In particular, the problem of magnetic helicity conservation both during the relaxation process and over longer timescales in driven systems is discussed. Relaxation mechanisms are reviewed and RFP dynamics is described in terms of cyclical diffusion, instability, and relaxation processes. Plasma relaxation interacts closely with heating and transport; its effects on ion heating and global confinement properties are discussed. Prospects including anticipated plasma performance in RFX are presented.